Most solar cells are in the form of a silicon substrate that has been metallized, i.e., provided with metal electrodes that are electrically conductive.
The electrodes of silicon solar cells are generally formed by printing a paste onto a silicon substrate. US-2011-0308597 A1 discloses a thick-film paste comprising a lead-tellurium-oxide powder for forming solar cell electrodes.
After printing, the substrate and the paste are fired in air to form a dense solid of electrically conductive traces. In the firing step, the glass frit can provide adhesion to the substrate and aid in the adhesion of subsequently soldered leads to the electrode. Good adhesion to the substrate and high solder adhesion of the leads to the electrode are desired for better performance of the solar cell as well as the manufacturability and reliability of the solar modules, especially when a lead-tellurium-oxide powder is contained in the paste.